A turbocharger customarily serves for the power augmentation of internal combustion engines by utilizing exhaust gas energy. For this purpose, the turbocharger consists of a compressor and a turbine which are interconnected via a shaft which is supported inside a bearing housing. During operation, the turbine is set in rotation by means of an exhaust gas flow and, via the shaft, drives the compressor which inducts and compresses air. The compressed air is directed into the engine, wherein as a result of the increased pressure during the induction cycle a large amount of air makes its way into the cylinder. As a result of this, the oxygen content which is required for the combustion of fuel correspondingly increases so that with each intake cycle more oxygen makes its way into the combustion chamber of the engine.
This leads to an increase of the maximum torque, as a result of which the power output, that is to say the maximum power at constant working volume, is increased. This increase especially allows the use of a more powerful engine with approximately the same dimensions or alternatively enables a reduction of the engine dimensions, that is to say enables a comparable power to be achieved with a smaller and lighter engine.
During the operation of a turbocharger, the shaft rotates with increasing engine rotational speed at high rotational velocity. As a result of the high rotational velocity, vibrations which for example are caused by the rotation of the shaft are transmitted to the bearing and its individual components. In order to minimize as far as possible an unwanted contact of the bearing cartridge with the bearing housing during this and to ensure a trouble-free operation of a turbocharger, use is customarily made of bearing units which by means of a so-called trapped oil film can damp the occurring vibrations.
A bearing device for a turbocharger is known from DE 35 31 313 A1. The bearing device comprises a bearing cartridge with a bearing which is designed as a ball bearing. The bearing is accommodated in a bush which in turn is positioned in a bearing housing. Recesses are introduced in the outer circumferential surface of the bush and also in the inner circumferential surface of the bearing housing and together form a hole. For the positioning of the bush inside the bearing housing, provision is made for a locking element, designed as a pin, which is inserted loosely into the recesses or into the hole.
As a result of the aforesaid design, a rotation of the outer bearing ring of the inserted bearing can certainly be prevented even at high rotational speeds of the shaft, but the use of a multiplicity of necessary separate bearing components and the cost intensive assembly effort which is associated therewith do not constitute a permanent solution for a bearing arrangement or for a turbocharger.